But while AD 1258 is the most
prominent example of the phenomenon we're addressing in the paper, we find a very similar story for AD 1452 and AD 1809 + AD 1815 (Tambora) sequence, where we know the volcano that erupted, and there is little doubt of a large and explosive tropical eruption.
Many ancient monuments were constructed with solar
phenomena in mind; for
example, stone megaliths accurately mark the summer solstice (some
of the most
prominent megaliths are located in Nabta Playa, Egypt, and at Stonehenge in England); the pyramid
of El Castillo at Chichén Itzá in Mexico is designed to cast shadows in the shape
of serpents climbing the pyramid at the vernal and autumn equinoxes.